CN102323494B - Method for distinguishing multiple harmonic sources - Google Patents

Abstract

The invention relates to a novel method for distinguishing multiple harmonic sources, which can be used for providing theoretical foundation for positioning a disturbance source in a multiple harmonic source system, managing harmonic waves, rewarding or punishing the harmonic waves and the like and has a broad application prospect and favorable social and economic benefits. The method comprises the following steps of: (1) defining a harmonic influence index; (2) solving the harmonic influence index; (3) acquiring and pre-processing data; and (4) selecting and analyzing the data.

Description

A kind of method for distinguishing multiple harmonic sources

Technical field

The present invention relates to a kind of new method for distinguishing multiple harmonic sources.

Background technology

Along with scientific and technological develop rapidly, new variation tendency has appearred in the formation of modern power network and load.A large amount of harmonic sources inject higher harmonic current and cause voltage distortion to electrical network, very large on safety and the economical operation impact of electric system.The harmonic wave that nonlinear-load produces not only can cause the security of electricity supply and use equipment itself to reduce, and can have a strong impact on the economical operation of electrical network and each user's interests.In order effectively to control the harmonic wave in electrical network, a kind of " rewards and punishments scheme " proposed in the world, its basic thought is: system and user arm's length transaction in specified scope, if system can not guarantee power supply quality, the user should obtain an indemnity; If user's contamination index worsens, system is guaranteeing to collect extra rejection penalty under the prerequisite of user's normal power supply, certainly in the situation that extra harmonic power in user's absorption system should give certain compensation and encouragement.Therefore, in strengthening electrical network, in the monitoring management process of harmonic wave, find harmonic source, judge perturbation direction, clear and definite harmonic wave responsibility separately, be a current main difficult technical urgently to be resolved hurrily.

The power quality problem caused by harmonic wave has caused electric system and user's extensive concern, and the supervision and management of strengthening the quality of power supply has become the common recognition of electricity supplying and using system.Domestic many electric power enterprises and user have built the electric energy quality monitoring platform in succession, characteristic index to the quality of power supply is carried out Real-Time Monitoring, can draw the situation of change of each key node quality of power supply in system thus, but this can not reflect why cause this power quality problem.Obtain the Monitoring Data of the quality of power supply, it is the first step of power quality analysis, the more important thing is that the Monitoring Data that how to effectively utilize quality of power supply platform and provide judges the source of power quality problem, and measure is targetedly taked in source, with the power quality problem occurred in the improvement system.How the mass data provided in the face of the electric energy quality monitoring platform, effectively analyze, be current electric energy quality monitoring system can bring into play it should effective main difficult technical.

Make a general survey of the research that domestic and international scientific worker does in the harmonic source identification field, mainly concentrate on and distinguish harmonic-producing load and system is located the influence degree of harmonic voltage distortion level to PCC (Point of Common Coupling point of common coupling), the harmonic emission level of single harmonic source is assessed, as shown in Figure 1, the data of Multi-harmonic Sources identification is considerably less and in Study system.But, in practical power systems, the harmonic wave at PCC place is the coefficient result of a plurality of harmonic sources often.For connecting the situation (as shown in Figure 2) of two or more harmonic sources on the same bus, can there is the problem interfered with each other between each harmonic source, its harmonic current may cancel out each other or strengthen.In containing the distribution system of a plurality of harmonic sources, when the power quality problem caused by harmonic wave occurs when, how accurately identification " problem " harmonic source is also determined the responsibility of each harmonic source, finding out the harmonic source that this power quality problem is had the greatest impact and administered, is that current harmonic wave detection field is worth a major issue of inquiring into.

Find only at present the responsibility evaluation studies of single harmonic source in document, it mainly concentrates on the harmonic impedance of assessing PCC place system side and harmonic source side, and research method can be divided into " intervention formula " and " non-intervention formula " two kinds." intervention formula " method has: 1. harmonic current injection: utilize the harmonic current injection device, certain subharmonic current that it is produced is injected into electric system by the points of common connection place that will measure, measurement, at this subharmonic voltage of this some generation, is tried to achieve the harmonic impedance of system thus.2. switch on-off circuit component Transient Method: the principle that the applying frequency response is estimated, utilize the transient process after the switch on-off network element, can be estimated system harmonic impedance.Because signal duration is shorter, thereby the data acquisition system is had higher requirement.3. the steady state method of PCC place fling-cut switch: at the PCC place, harmonic voltage and harmonic current during by the measuring switch open and close estimate harmonic impedance.Because system is not less with the situation of survey load, the time period is shorter, and therefore the estimation accuracy for user's harmonic emission level has considerable influence.4. in the method for estimation of user's side parallel impedance: user's side by switch in parallel on an impedance, harmonic voltage and the harmonic current at the PCC place during measuring switch open and close, calculate harmonic impedance with this, precision is higher than the steady state method of PCC place fling-cut switch." non-intervention formula " method has: the 1. method based on power delivery: the harmonic current of order by measuring PCC, and, in conjunction with the method based on power delivery, assess user's harmonic emission level.2. Fluctuation Method: the method for estimation based on tested magnitude of a voltage fluctuation to the symbolic feature of current wave momentum ratio.Utilize the fluctuation estimation harmonic impedance that the variation of certain side harmonic current causes at PCC point in a time period, then calculate the harmonic emission level of user's side.3. the data tracking estimation technique: harmonic voltage and harmonic current data are measured by the PCC point place in the system equivalent circuit, then by various mathematical methods, estimate harmonic impedance.4. reference impedance method: utilize reference impedance, the method for harmonic emission level is estimated in the variation that the variation of harmonic impedance is converted to harmonic current source.The method need not EVAC (Evacuation Network Computer Model) normally be moved, but needs in advance reference impedance and harmonic source are had to initial estimation.

Generally speaking, the thinking of the harmonic emission level of single harmonic source being assessed based on equivalent-circuit model has been taked in research work in the past mostly, although carrying out the Position Research of harmonic source based on equivalent-circuit model is very useful exploration, but, due to the continuous variation of load, electrical network parameter and system conditions, still there is certain difficulty in the Exact Equivalent Circuit of setting up system side and harmonic source side.

It is less that research in the past relates to the research of multiple-harmonic-source harmonic divisions of responsibility can, and, in practical power systems, the harmonic wave at PCC place is the coefficient result of a plurality of harmonic sources often.For connecting the situation of two or more harmonic sources on the same bus, can there is the problem interfered with each other between each harmonic source, its harmonic current may cancel out each other or strengthen, so might not be linear relationship between the harmonic current of each harmonic source and its harmonic wave responsibility that should bear.In containing the distribution system of a plurality of harmonic sources, when the power quality problem caused by harmonic wave occurs when, how accurately identification " problem " harmonic source is also determined the harmonic wave responsibility of each harmonic source, finding out the harmonic source that this power quality problem is had the greatest impact and administered, is the technical barrier that current harmonic wave detection field not yet effectively solves.

Summary of the invention

Purpose of the present invention is exactly the deficiency for current Multi-harmonic Sources identification problem research, a kind of new method for distinguishing multiple harmonic sources is proposed, it can be the location of disturbing source in the Multi-harmonic Sources system, the improvement of harmonic wave and the rewards and punishments enforcement of harmonic wave etc. theoretical foundation is provided, and has broad application prospects and good economic results in society.

For achieving the above object, the present invention adopts following technical scheme:

A kind of method for distinguishing multiple harmonic sources, its step is:

(1) definition harmonic wave responsibility index

In supposing the system, the harmonic problem at nodes X place is to be produced by n " suspicious harmonic-producing load " acting in conjunction, for the h subharmonic, records the harmonic current I of n " suspicious harmonic-producing load " node _h1, I _h2, I _h3i _hn; The h subharmonic voltage at nodes X place

harmonic impedance [Z according to system _h] calculate,

The h subharmonic voltage at nodes X point place is divided into to two parts: a part is produced by harmonic-producing load i

the background harmonics that another part is produced by other harmonic-producing loads

Wherein, I _hih subharmonic current for the harmonic-producing load node i;

for the harmonic impedance between node i and nodes X; for other harmonic-producing load nodes except the harmonic-producing load node i and the harmonic impedance between nodes X.

The h subharmonic voltage that harmonic-producing load i produces at X point place

h subharmonic voltage to the nodes X place

contribution pass through

on projective representation's (as shown in Figure 3), the harmonic wave responsibility index of harmonic-producing load i to the h subharmonic voltage at X place

be defined as:

${{\mathrm{HF}}_i}^X=\frac{\left|{\stackrel{\→}{V}}_{\mathrm{hi}}^X\right|}{\left|{\stackrel{\→}{V}}_h^X\right|}\cos \mathrm{\β}---\left(2\right)$

Wherein β is

angle;

(2) ask for harmonic wave responsibility index

Actual waveform to key node in electric system is sampled, and obtains harmonic data, and then calculates harmonic wave responsibility index

, set up following equation:

Y＝Sθ+ε (3)

Wherein, Y serves as reasons

the matrix parameter of structure, $Y=[{\left|{\stackrel{\→}{V}}_h^X\left(t_1\right)\right|}^2{\left|{\stackrel{\→}{V}}_h^X\left(t_2\right)\right|}^2\·\·\·{\left|{\stackrel{\→}{V}}_h^X\left(t_m\right)\right|}^2],$

(k=1,2 ... m) be each sampling instant t ₁, t ₂..., t _mthe h subharmonic voltage at nodes X place amplitude;

S serves as reasons | I _hi(t _k) | the matrix parameter of structure,

(k=1,2 ... m) be the amplitude of the h subharmonic current of each sampling instant node i;

$\mathrm{\θ}={\left[\begin{array}{ccc}{\left|{\stackrel{\→}{E}}_h\right|}^2& -2\left|Z_{\mathrm{hi}}^X\right|\left|{\stackrel{\→}{E}}_h\right|\mathrm{COS}\left({\mathrm{\α}}_{\mathrm{eq}}\right)& {\left|Z_{\mathrm{hi}}^X\right|}^2\end{array}\right]}^T,$ α _eqfor

with

the mean value of angle α, for

amplitude, ε uses α _eqthe error that replaces α to produce; for the harmonic impedance between node i and X.

In above-mentioned equation, when carrying out correlation analysis, suppose background harmonics

remain unchanged, by least square method, estimate unknown parameter θ, substitution (2) can obtain,

${{\mathrm{HF}}_i}^X\left(t_k\right)=\frac{{\left|Z_{\mathrm{hi}}^X\right|}^2{\left|I_{\mathrm{hi}}\left(t_k\right)\right|}^2+\left|{\stackrel{\→}{V}}_h^X{\left(t_k\right)}^2\right|-{\left|{\stackrel{\→}{E}}_h\right|}^2}{2{\left|{\stackrel{\→}{V}}_h^X\left(t_k\right)\right|}^2}\×100\%---\left(4\right)$

that mean is t _kthe harmonic wave responsibility index of moment harmonic-producing load i to the h subharmonic voltage of nodes X, and one section interior average harmonic wave responsibility index of special time is:

${{\mathrm{HF}}_i}^X=(\frac{1}{2}+\frac{1}{m}\underset{k=1}{\overset{m}{\mathrm{\Σ}}}\frac{{-\left|{\stackrel{\→}{E}}_h\right|}^2+{\left|Z_{\mathrm{hi}}^X\right|}^2{\left|I_{\mathrm{hi}}\left(t_k\right)\right|}^2}{2{\left|{\stackrel{\→}{V}}_h^X\right|}^2})\×100\%---\left(5\right)$

The total degree of m for measuring, as long as record the h subharmonic current I of suspicious harmonic-producing load i _hih subharmonic voltage with the nodes X place

just can calculate the harmonic wave responsibility of load i according to above-mentioned equation;

(3) collection of data and pre-service

Main harmonic-producing load point in electric system installs and measures device, gathers single-phase voltage and the current signal of key node simultaneously, and removes the signal that contains obvious noise and transient interference;

(4) carry out selection and the analysis of data

Finding out only have one harmonic current of " suspicious harmonic-producing load " has the time period of larger variation, taking-up meets the node voltage of time period of this requirement and the data of electric current are carried out correlation analysis, at the h subharmonic current of this time period internal loading i, change greatly and the variation of the h subharmonic current of all the other loads is less, actual measurement voltage and current data to the selected time period gone out are carried out Fourier decomposition, draw fundamental component and the each harmonic component of each variable, estimate unknown parameter θ according to formula (3), can calculate again the harmonic wave responsibility index of the suspicious harmonic-producing load i meaned with the number percent form according to formula (4) and (5)

In described step (3), gather once every 3 seconds, gathers 6 cycles at every turn, and each cycle gathers 128 points; The voltage and current data that collect are carried out to pre-service, remove the data segment that contains transient state and the signal that obvious noise is arranged.

In described step (4), according to the load condition in practical application, the variation of h subharmonic current is set as fluctuation between 5%～10%.

The invention has the beneficial effects as follows:

(1) for there is the phenomenon of a plurality of harmonic sources in modern complicated electric power system simultaneously, a kind of harmonic wave divisions of responsibility can of Multi-harmonic Sources and the effective ways of identification are proposed, it will limit and administer the harmonic pollution based theoretical for setting up fair effectively harmonic wave rewards and punishments mechanism and standard in the Multi-harmonic Sources system, and select suitable place for power supply department and take harness of harmonic wave that reference is provided;

(2) method is directly from the historical measured data of harmonic voltage and electric current, the data dependence analysis method of employing based on statistical law, the harmonic wave responsibility of assessment Multi-harmonic Sources, the model existed while having overcome in the past based on Model Distinguish single harmonic source is difficult for accurately asking for and the problem such as temporal evolution;

(3) the needed data of method easily gather, can obtain based on electric power enterprise and the existing electric energy quality monitoring platform of user, the Monitoring Data that can effectively utilize quality of power supply platform to provide, so the method is a kind of senior power quality analysis based on quality of power supply platform;

(4) method, through tight mathematical derivation, has very strong theory support, and the method is expected to contribute for the intellectuality progress of the table meter systems of China's intelligent power network and power distribution network.

The accompanying drawing explanation

Fig. 1 is traditional harmonic source location and detects the equivalent model used;

The harmonic wave divisions of responsibility can problem schematic diagram that Fig. 2 is Multi-harmonic Sources;

Fig. 3 is harmonic voltage projection phasor graph;

Fig. 4 is time series split plot design schematic diagram;

Fig. 5 is the IEEE13 node system.

Embodiment

Below in conjunction with accompanying drawing and example, the present invention will be further described.

Step of the present invention is:

(1) definition harmonic wave responsibility index

In supposing the system, the harmonic problem at nodes X place is to be produced by n " suspicious harmonic-producing load " acting in conjunction, for the h subharmonic, records the harmonic current I of n " suspicious harmonic-producing load " node _h1, I _h2, I _h3i _hn; The h subharmonic voltage at nodes X place

harmonic impedance [Z according to system _h] calculate,

The h subharmonic voltage at nodes X place is divided into to two parts: a part is produced by harmonic-producing load i

, the background harmonics that another part is produced by other harmonic-producing loads

Wherein, I _hih subharmonic current for the harmonic-producing load node i;

for the harmonic impedance between node i and nodes X; for other harmonic-producing load nodes except the harmonic-producing load node i and the harmonic impedance between nodes X.

The h subharmonic voltage that harmonic-producing load i produces at X point place

h subharmonic voltage to the nodes X place

contribution pass through

on projective representation's (as shown in Figure 3), the harmonic wave responsibility index of harmonic-producing load i to the h subharmonic voltage at X place

be defined as:

${\mathrm{HF}}_i^X=\frac{\left|{\stackrel{\→}{V}}_{\mathrm{hi}}^X\right|}{\left|{\stackrel{\→}{V}}_h^X\right|}\cos \mathrm{\β}---\left(2\right)$

Wherein β is

angle;

(2) ask for harmonic wave responsibility index.

Actual waveform to key node in electric system is sampled, and obtains harmonic data, and then calculates harmonic wave responsibility index

, set up following equation:

Y＝Sθ+ε (3)

Wherein, Y serves as reasons

the matrix parameter of structure, $Y=[{\left|{\stackrel{\→}{V}}_h^X\left(t_1\right)\right|}^2{\left|{\stackrel{\→}{V}}_h^X\left(t_2\right)\right|}^2\·\·\·{\left|{\stackrel{\→}{V}}_h^X\left(t_m\right)\right|}^2],$

(k=1,2 ... m) be each sampling instant t ₁, t ₂..., t _mthe h subharmonic voltage at nodes X place

amplitude;

S serves as reasons | I _hi(t _k) | the matrix parameter of structure,

(k=1,2 ... m) be the amplitude of the h subharmonic current of each sampling instant node i;

$\mathrm{\θ}={\left[\begin{array}{ccc}{\left|{\stackrel{\→}{E}}_h\right|}^2& -2\left|Z_{\mathrm{hi}}^X\right|\left|{\stackrel{\→}{E}}_h\right|\mathrm{COS}\left({\mathrm{\α}}_{\mathrm{eq}}\right)& {\left|Z_{\mathrm{hi}}^X\right|}^2\end{array}\right]}^T,$ α _eqfor

with the mean value of angle α,

for

amplitude, ε uses α _eqthe error that replaces α to produce;

for the harmonic impedance between node i and X.

In above-mentioned equation, when carrying out correlation analysis, suppose background harmonics

remain unchanged, by least square method, estimate unknown parameter θ, substitution (2) can obtain,

${{\mathrm{HF}}_i}^X\left(t_k\right)=\frac{{\left|Z_{\mathrm{hi}}^X\right|}^2{\left|I_{\mathrm{hi}}\left(t_k\right)\right|}^2+\left|{\stackrel{\→}{V}}_h^X{\left(t_k\right)}^2\right|-{\left|{\stackrel{\→}{E}}_h\right|}^2}{2{\left|{\stackrel{\→}{V}}_h^X\left(t_k\right)\right|}^2}\×100\%---\left(4\right)$

that mean is t _kthe harmonic wave responsibility index of moment harmonic-producing load i to the h subharmonic voltage of nodes X, and one section interior average harmonic wave responsibility index of special time is:

${{\mathrm{HF}}_i}^X=(\frac{1}{2}+\frac{1}{m}\underset{k=1}{\overset{m}{\mathrm{\Σ}}}\frac{{-\left|{\stackrel{\→}{E}}_h\right|}^2+{\left|Z_{\mathrm{hi}}^X\right|}^2{\left|I_{\mathrm{hi}}\left(t_k\right)\right|}^2}{2{\left|{\stackrel{\→}{V}}_h^X\right|}^2})\×100\%---\left(5\right)$

The total degree of m for measuring, as long as record the h subharmonic current I of suspicious harmonic-producing load i _hih subharmonic voltage with the nodes X place

, according to above-mentioned equation just can calculate the load i the harmonic wave responsibility;

(3) collection of data and pre-service

Main harmonic-producing load point in electric system installs and measures device, gathers single-phase voltage and the current signal of key node simultaneously, and removes the signal that contains obvious noise and transient interference;

(4) selection of data and analysis

Define the hypothesis of doing according to influence index, need to find out the time period of the harmonic current variation of only having a harmonic-producing load.The key of data screening is to find out the time period that only have one harmonic current of " suspicious harmonic-producing load " has larger variation.Take Fig. 4 as example, in order to find out the impact of load 1 subharmonic voltage of the h on the nodes X place, need to find out a time period, change at the h of this time period internal loading 1 subharmonic current 2,3 the h subharmonic current of loading greatly and change less (for example can be set as fluctuating and be less than 5%～10%).Concrete grammar is, first respectively to load 2 and the h subharmonic current of load 3 change the less time and carry out mark, then get the common factor of these time periods.In figure, the data in T1, T2 time period meet the demands.Taking-up meets the node voltage of time period of this requirement and the data of electric current are carried out correlation analysis.

Actual measurement voltage and current data to the selected time period gone out are carried out Fourier decomposition, draw each variable fundamental component and each harmonic component, estimate unknown parameter θ according to formula (3), then can calculate the harmonic wave responsibility index of the suspicious harmonic-producing load meaned with the number percent form according to formula (4) and (5)

in like manner, same process can be used for the analysis to other harmonic-producing load.

Simulating, verifying

Carry out simulating, verifying above-mentioned theory method by IEEE13 node standard example system (as shown in Figure 5).This system has 2 generators, 1 balance node, 1 PV node and 7 PQ nodes.Load 7,10,13 is connected to harmonic-producing load, and node 3,7,10,13 is for observing node.All PQ nodes meritorious, idle random variation in ± 110% rated range, carried out 1000 emulation, generated the harmonic wave responsibility and assessed basic data used, on this basis suspicious harmonic-producing load assessed in the harmonic wave responsibility of observation point.The assessment result that will draw with institute's extracting method and the precise results calculated with harmonic trend contrast, and comparing result is shown in table 1-4.(and annotates: wherein negative sign means the reduce effect of harmonic-producing load to observation point harmonic distortion voltage.) result shows, the method can be assessed the harmonic wave responsibility of harmonic-producing load more exactly.

The harmonic wave responsibility (%) of the suspicious harmonic-producing load of table 1 to node 3

The harmonic wave responsibility (%) of the suspicious harmonic-producing load of table 2 to node 7

The harmonic wave responsibility (%) of the suspicious harmonic-producing load of table 3 to node 10

The harmonic wave responsibility (%) of the suspicious harmonic-producing load of table 4 to node 13

Claims (3)

1. a method for distinguishing multiple harmonic sources, is characterized in that, its process is:

(1) definition harmonic wave responsibility index

The harmonic problem at supposing the system nodes X place is to be produced by n " suspicious harmonic-producing load " acting in conjunction, for the h subharmonic, records the harmonic current I of n " suspicious harmonic-producing load " node _h1, I _h2, I _h3i _hn; The h subharmonic voltage at nodes X place harmonic impedance [Z according to system _h] calculate,

The h subharmonic voltage at nodes X place is divided into to two parts: a part is produced by harmonic-producing load i

the background harmonics that another part is produced by other harmonic-producing loads

Wherein, I _hih subharmonic current for the harmonic-producing load node i;

for the harmonic impedance between node i and nodes X; for other harmonic-producing load nodes except the harmonic-producing load node i and the harmonic impedance between nodes X;

The h subharmonic voltage that harmonic-producing load i produces at the X place

h subharmonic voltage to the nodes X place

contribution pass through

on projective representation, the harmonic wave responsibility index of harmonic-producing load i to the h subharmonic voltage at X place

be defined as:

${\mathrm{HF}}_i^X=\frac{\left|{\stackrel{\→}{V}}_{\mathrm{hi}}^X\right|}{\left|{\stackrel{\→}{V}}_h^X\right|}\cos \mathrm{\β}---\left(2\right)$

Wherein β is

angle;

(2) ask for harmonic wave responsibility index

Actual waveform to key node in electric system is sampled, and obtains harmonic data, and then calculates harmonic wave responsibility index

set up following equation:

Y＝Sθ+ε (3)

Wherein, Y serves as reasons

the matrix parameter of structure, $Y=[{\left|{\stackrel{\→}{V}}_h^X\left(t_1\right)\right|}^2{\left|{\stackrel{\→}{V}}_h^X\left(t_2\right)\right|}^2\·\·\·{\left|{\stackrel{\→}{V}}_h^X\left(t_m\right)\right|}^2],$

(k=1,2 ... m) be each sampling instant t ₁, t ₂..., t _mthe h subharmonic voltage at nodes X place

amplitude;

S serves as reasons | I _hi(t _k) | the matrix parameter of structure,

(k=1,2 ... m) be the amplitude of the h subharmonic current of each sampling instant node i;

$\mathrm{\θ}={\left[\begin{array}{ccc}{\left|{\stackrel{\→}{E}}_h\right|}^2& -2\left|Z_{\mathrm{hi}}^X\right|\left|{\stackrel{\→}{E}}_h\right|\mathrm{COS}\left({\mathrm{\α}}_{\mathrm{eq}}\right)& {\left|Z_{\mathrm{hi}}^X\right|}^2\end{array}\right]}^T,$ α _eqfor

the mean value of angle α,

for

amplitude, ε uses α _eqthe error that replaces α to produce; for the harmonic impedance between node i and X;

In above-mentioned equation, when carrying out correlation analysis, suppose background harmonics

remain unchanged, by least square method, estimate unknown parameter θ, substitution (2),

${\mathrm{HF}}_i^X\left(t_k\right)=\frac{{\left|Z_{\mathrm{hi}}^X\right|}^2{\left|I_{\mathrm{hi}}\left(t_k\right)\right|}^2+\left|{\stackrel{\→}{V}}_h^X{\left(t_k\right)}^2\right|-{\left|{\stackrel{\→}{E}}_h\right|}^2}{2{\left|{\stackrel{\→}{V}}_h^X\left(t_k\right)\right|}^2}\×100\%---\left(4\right)$

that mean is t _kthe harmonic wave responsibility index of moment harmonic-producing load i to the h subharmonic voltage of nodes X, and one section interior average harmonic wave responsibility index of special time is:

${\mathrm{HF}}_i^X=(\frac{1}{2}+\frac{1}{m}\underset{k=1}{\overset{m}{\mathrm{\Σ}}}\frac{{-\left|{\stackrel{\→}{E}}_h\right|}^2+{\left|Z_{\mathrm{hi}}^X\right|}^2{\left|I_{\mathrm{hi}}\left(t_k\right)\right|}^2}{2{\left|{\stackrel{\→}{V}}_h^X\left(t_k\right)\right|}^2})\×100\%---\left(5\right)$

The total degree of m for measuring, as long as record the h subharmonic current I of suspicious harmonic-producing load i _hih subharmonic voltage with the nodes X place

, according to above-mentioned equation calculate the load i the harmonic wave responsibility;

(3) collection of data and pre-service

Main harmonic-producing load point in electric system installs and measures device, gathers single-phase voltage and the current signal of key node simultaneously, and removes the signal that contains obvious noise and transient interference;

(4) carry out selection and the analysis of data

Finding out only have one harmonic current of " suspicious harmonic-producing load " has the time period of larger variation, taking-up meets the node voltage of time period of this requirement and the data of electric current are carried out correlation analysis, at the h subharmonic current of this time period internal loading i, change greatly and the variation of the h subharmonic current of all the other loads is less, actual measurement voltage and current data to the selected time period gone out are carried out Fourier decomposition, draw fundamental component and the each harmonic component of each variable, estimate unknown parameter θ according to formula (3), calculate again the harmonic wave responsibility index of the suspicious harmonic-producing load meaned with the number percent form according to formula (4) and (5)

2. method for distinguishing multiple harmonic sources as claimed in claim 1, is characterized in that, in described step (3), gather once every 3 seconds, gathers 6 cycles at every turn, and each cycle gathers 128 points; The voltage and current data that collect are carried out to pre-service, remove the data segment that contains transient state and the signal that obvious noise is arranged.

3. method for distinguishing multiple harmonic sources as claimed in claim 1, is characterized in that, in described step (4), according to the load condition in practical application, the variation of h subharmonic current is set as fluctuation between 5%～10%.

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